How to read Chest X-ray?

How To Read a Chest X-Ray (CXR)

Every physician has their own method of evaluating films. Most will tell you that it doesn't matter so much what method you chose, but rather that you approach an image systematically, the same way every time, in order to ensure the fewest possible omissions and errors. I have found the following method effective, feel free to adapt and post comments.

1. Identify your pt: DOB, CC, HPI
2. Use the "PIER" mnemonic to assess for adequacy of the film. Ask yourself is the film worth "pier-ing" into? <-- to remember the mnemonic
1. Position: Typically, upright PA and lateral. Sick patients will have the fuzzier supine AP (because the film is slid under their chest as they are lying down).
   
2. Inspiration: Count the visible ribs. Lung fields should extend to about the 10th or 11th rib.
3. Exposure: If the film is penetrated enough, you should be able to make out the spinous processes "inside" the vertebrae. If the film is underexposed/too white, you won't be able to see them. If the film is overexposed/too black, bony details will be lost.
   
4. Rotation: Evaluate the clavicals. They should appear symmetric and equal in length. Now systematically work through the x-ray.
3. Evaluate the film. Here is one popular pneumonic. See the links at the bottom of the post for more CXR guides with images.
   
• A = Airway: are the trachea and mainstem bronchi patent; is the trachea midline?
  
• B = Bones: are the clavicles, ribs, and sternum present and are there fractures, lytic lesions?
  
• C = Cardiac silhouette: is the diameter of the heart > ½ thoracic diameter (enlarged)?
• D = Diaphragm: are the costophrenic and costocardiac margins sharp? is one hemidiaphragm enlarged over another? is free air present beneath the diaphragm?
• E = Effusion/empty space: is either present?
• F = Fields (lungs): are there infiltrates, increased interstitial markings, masses, air bronchograms, increased vascularity, or silhouette signs?
• G = Gastric bubble: is it present and on the correct (left) side?
• H = Hilar region: is there increased hilar lymphadenopathy?
• Now check the places you forgot to look:
• Soft Tissue - Breast shadows, supraclavicular regions, axillae, chest wall. Look for thickness, subcutaneous emphysema (air bubbles-dark spots), calcifications (bright spots).
• Behind the heart
• The apices
• Under the clavicles
• The costophrenic angle and the cardiophrenic angle and interface
4. Types of lung densities:
• alveolar: patchy, poorly marginated. Represents material other than air in the airspaces. May see "air bronchograms"-black lines representing air-filled bronchi amidst water-density alveoli. May note "silhouette signs"-organs' margins blurred by dense material in alveoli of nearby lung tissue.
• interstitial: thickening of bronchi, septae. Linear or finely granular patterns of abnormal shadows. "Kerley's B-lines" (not "curly" B-lines) are thickening of interlobular septae and are small, bright, horizontal lines seen esp. towards the bases of the lungs. They are associated with CHF. The interstitial pattern is seen in CHF, interstitial fibrosis, cancer, inflammation.
• atelectasis: loss of volume leads to a shift of interlobar fissures & mediastinum towards the collapsed region.
• nodules: one or more dense, bright, round lesions. Adenoma, granuloma, cancer, cyst, lymph node, etc.
• other: abscess (lucency within density, air-fluid level); pneumatoceles (air-containing spaces seen with some pneumonias); honeycombing (airspaces w/thick septae)
• Also check out:
• CXR 1
• CXR 2